It has become known to use cuffs or sealing members internally of a conduit to seal joints or damaged areas of a conduit to prevent infiltration into or leakage from the conduit or pipe. Conduits of this character typically carry water, wastewater, sewage, natural gas, petroleum and the like. Since these pipe are normally located underground, they are susceptible to damage from the environment, corrosion, cracking or leaks at the joints. In many cases it is not possible to expose or excavate the pipe for repair because of the necessary excavation would disrupt highways, building and the like. In these cases it has become acceptable to use trenchless, internal joint or damage sealing means. It is not uncommon to internally seal or repair pipes of diameters from 14 inches to 216 inches using elastomeric sealing materials. See, e.g., U.S. Pat. No. 4,685,704. The seals are placed within the pipes by skilled technicians who traverse the pipe to the damaged or leaking area.
The sealing installation process is relatively uncomplicated. The elastomeric seal generally is circular in nature, but can be dimensioned to assume other pipe shapes. The elastomeric material of the seal is typically selected for the type of material flowing through the pipe. For example, ethylene propylene diene monomers rubber is used for waste water and potable water, butadiene acrylonitrile rubber is used in natural gas applications. Normally, the seal is provided with internal annular recesses designed to accommodate metal bands which are made from stainless steel, carbon steel, or special alloys. Once the seal is positioned over the joint or leak by hand or pneumatic means, the bands are placed in to the annular grooves. A special hydraulic press is used to expand the band in the groove to compress the seal against the pipe. Special wedges or inserts are used to maintain the position of the band to maintain compression and provide a fluid tight seal.
Typically, the seals are manufactured by extrusion through a die containing the desired profile or molded, however, this is relatively expensive. The seal is extruded in the form of a belt with a cross-section in which the profile the sealing ribs located adjacent to but spaced apart from the edges, and under the band accommodating grooves. A web membrane is located between the rib sections and can be of a varying lengths to accommodate both joints and areas subject to damage or leakage. The belt is cut uneven to fit the inside circumference of the pipe, tube or tanks. Similarly, belts can be joined by adhesive, overlapping or vulcanizing to form a continuous seal that is circular or in other geometric shape.
While the use of internal sealing means such as disclosed in U.S. Pat. No. 4,685,704 afford more efficient and cost effective repair, such repairs are not inexpensive. It is therefore desirable to make the repair as well as the seal itself as trouble free and long lasting as possible. Accordingly, it is an object of the present invention to provide an internal pipe seal which can be installed using conventional hydraulic presses and bands, but provides a sealing profile which affords more effective sealing than current seal profiles. It is a further object of the invention to provide a novel seal, seal profile, and expansion band that locks in place when subjected to high velocity or low velocity flow of material transported through a pipe or struck by debris moving within a pipe or conduit. It is also an objective of the invention to provide an external seal member having a structure that controls the cold flow of elastomeric material under compression of the expansion bands.